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Ophiostoma novo-ulmi je parazitická vřeckovýtrusá houba. Prorůstáním cévních svazků jilmů způsobuje již od 60. let 20. století onemocnění zvané Grafióza jilmu. Byla poprvé popsána v roce 1991 jako nový agresivní druh, který vznikl pravděpodobně mutací její předchůdkyně Ophiostoma ulmi. Ta má na svědomí pandemii grafiózy jilmů od 20. do 60. let 20. století.
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Ophiostoma novo-ulmi is a species of fungus in the family Ophiostomataceae. It is one of the key causative agents associated with Dutch Elm Disease (DED),[1] along with Ophiostoma ulmi and Ophiostoma himal-ulmi.
Dutch Elm Disease was first identified in Europe during the early 1900s and by the 1940s the disease had spread throughout Europe and into the United States and Canada.[2] Elm trees (Ulmus) were heavily used as a trade commodity in logging practices in the late 1800s-1900s. Historically, these trees have seen widespread use as a building material in products such as wheels, chairs, ships, and coffins.[3] Wood from Ulmus trees has been favored for building due to the trees' ability to withstand prolonged exposure to water without rotting. The adaptability of this tree along with its multitude of applications for building opened up its demand in trading.
It has been determined that Ophiostoma ulmi and Ophiostoma novo-ulmi have evolved separately from each other in different regions of the world though it has been thought that novo-ulmi has obtained genes from Ophiostoma ulmi making it a more effective pathogen for Elm trees.
O. ulmi caused one of the first pandemics of the species, within Europe and North America, between 1910-1940 and caused 10-40% death of genus Ulmus. This pandemic was followed by a second pandemic beginning in the 1940s caused by the O. novo-ulmi species. This pathogen proved to be more invasive and aggressive in comparison to other species associated with the disease. The introduction of O. novo-ulmi is traced back to the logging trade among regions. Logs infected with the pathogen and traded throughout Europe and intercontinentally leading to the spread of the fungus. O. novo-ulmi came in contact with various amounts of highly susceptible host species in Europe, western Asia and North America making it easier to spread Dutch Elm Disease. Bark beetles have become a vector for the fungus to spread among elm tree groves. The bark beetles often carry spores on their bodies. The spores are easily transferred via twig crotches where they obstruct vessels by gums, tyloses, fungal material and foliage wilts, causing the tree to die.[1] These beetles complete an entire life cycle in one elm tree until the tree can no longer support the beetles. Following this young beetles will find healthy trees to inhabit which they infect with spores they carry from the previous elm tree. When the beetles feed on the tree they introduce the fungi to the food and water supply of the tree via the branches connecting to the xylem of the tree, allowing rapid spread throughout the vascular tissue of the tree.[4]
Once the fungus has been introduced to the vascular tissue of the tree it spreads rapidly, causing death as a result of the tree's natural immune response. In the xylem vessels the fungus produces yeast-like spores and multicellular filamentous hyphae. This allows for vertical movement in the vessels, then moves laterally to infect neighboring vessels.[4] Logs that contain both the fungi and beetles can transmit the pathogen to native species at much higher rate and cause a greater range for invasion. Furthermore, O. novo-ulmi can also spread from infected trees to healthy trees through root grafts. When the roots of adjacent elm trees come into contact with each other underground, the fungus can move from the infected tree to the healthy tree through these root connections.[2] It can also invade an elm tree through wounds on the bark or branches. This can occur naturally through storms, animal activity, or human interventions such as pruning or other tree care practices. The spores of the fungus can enter the tree through these wounds and establish an infection.[2] Once inside the tree, O. novo-ulmi grows in the water-conducting vessels of the tree, blocking the flow of water and nutrients, which eventually leads to wilting, yellowing of leaves, and tree death.[2] The fungus also produces toxic compounds that further contribute to the damage to the tree's vascular system and overall health.
O. novo-ulmi infestation can spread rapidly, causing severe damage and death to susceptible elm trees. Effective management strategies, such as tree removal, pruning, and applications, may be used to control the spread of the disease in affected areas.[4] Early detection and prevention are key in managing Dutch elm disease caused by O. novo-ulmi.
Ophiostoma novo-ulmi is a species of fungus in the family Ophiostomataceae. It is one of the key causative agents associated with Dutch Elm Disease (DED), along with Ophiostoma ulmi and Ophiostoma himal-ulmi.
Dutch Elm Disease was first identified in Europe during the early 1900s and by the 1940s the disease had spread throughout Europe and into the United States and Canada. Elm trees (Ulmus) were heavily used as a trade commodity in logging practices in the late 1800s-1900s. Historically, these trees have seen widespread use as a building material in products such as wheels, chairs, ships, and coffins. Wood from Ulmus trees has been favored for building due to the trees' ability to withstand prolonged exposure to water without rotting. The adaptability of this tree along with its multitude of applications for building opened up its demand in trading.
It has been determined that Ophiostoma ulmi and Ophiostoma novo-ulmi have evolved separately from each other in different regions of the world though it has been thought that novo-ulmi has obtained genes from Ophiostoma ulmi making it a more effective pathogen for Elm trees.
O. ulmi caused one of the first pandemics of the species, within Europe and North America, between 1910-1940 and caused 10-40% death of genus Ulmus. This pandemic was followed by a second pandemic beginning in the 1940s caused by the O. novo-ulmi species. This pathogen proved to be more invasive and aggressive in comparison to other species associated with the disease. The introduction of O. novo-ulmi is traced back to the logging trade among regions. Logs infected with the pathogen and traded throughout Europe and intercontinentally leading to the spread of the fungus. O. novo-ulmi came in contact with various amounts of highly susceptible host species in Europe, western Asia and North America making it easier to spread Dutch Elm Disease. Bark beetles have become a vector for the fungus to spread among elm tree groves. The bark beetles often carry spores on their bodies. The spores are easily transferred via twig crotches where they obstruct vessels by gums, tyloses, fungal material and foliage wilts, causing the tree to die. These beetles complete an entire life cycle in one elm tree until the tree can no longer support the beetles. Following this young beetles will find healthy trees to inhabit which they infect with spores they carry from the previous elm tree. When the beetles feed on the tree they introduce the fungi to the food and water supply of the tree via the branches connecting to the xylem of the tree, allowing rapid spread throughout the vascular tissue of the tree.
Once the fungus has been introduced to the vascular tissue of the tree it spreads rapidly, causing death as a result of the tree's natural immune response. In the xylem vessels the fungus produces yeast-like spores and multicellular filamentous hyphae. This allows for vertical movement in the vessels, then moves laterally to infect neighboring vessels. Logs that contain both the fungi and beetles can transmit the pathogen to native species at much higher rate and cause a greater range for invasion. Furthermore, O. novo-ulmi can also spread from infected trees to healthy trees through root grafts. When the roots of adjacent elm trees come into contact with each other underground, the fungus can move from the infected tree to the healthy tree through these root connections. It can also invade an elm tree through wounds on the bark or branches. This can occur naturally through storms, animal activity, or human interventions such as pruning or other tree care practices. The spores of the fungus can enter the tree through these wounds and establish an infection. Once inside the tree, O. novo-ulmi grows in the water-conducting vessels of the tree, blocking the flow of water and nutrients, which eventually leads to wilting, yellowing of leaves, and tree death. The fungus also produces toxic compounds that further contribute to the damage to the tree's vascular system and overall health.
O. novo-ulmi infestation can spread rapidly, causing severe damage and death to susceptible elm trees. Effective management strategies, such as tree removal, pruning, and applications, may be used to control the spread of the disease in affected areas. Early detection and prevention are key in managing Dutch elm disease caused by O. novo-ulmi.
Ophiostoma novo-ulmi is een schimmel die behoort tot de orde Ophiostomatales van de ascomyceten. De schimmel veroorzaakt iepenziekte. Ophiostoma novo-ulmi is pas in de jaren zeventig voor het eerst waargenomen en tast ook de tegen Ophiostoma ulmi resistente rassen 'Commelin' en 'Groeneveld' aan. De schimmel heeft n = 8 chromosomen.
Er zijn twee ondersoorten van Ophiostoma novo-ulmi:
De schimmel groeit in houtvaten van de boom. De boom produceert als reactie thyllen, een gomblaas om de groei van de schimmel te stoppen, maar daardoor raken die vaten ook verstopt. De schimmel kan van het ene houtvat in het andere komen waardoor er zoveel houtvaten verstopt raken dat de boom afsterft. De schimmel wordt verspreid door de grote en de kleine iepenspintkever (Scolytus scolytus en S. multistriatus).
De Euraziatische ondersoort (EAN) Ophiostoma novo-ulmi subsp. novo-ulmi verscheen voor het eerst in Europa in de Moldavië-regio in de 1940-jaren. De Noord-Amerikaanse ondersoort (NAN) Ophiostoma novo-ulmi subsp. americana verscheen ook in de 1940-jaren voor het eerst in de zuidelijke streken van de Grote Meren en werd omstreeks 1960 ingevoerd in Groot-Brittannië vermoedelijk met een scheepslading iepenhout. Ze werden verder over Europa verspreid door de iepenspintkevers.[1] Ophiostoma novo-ulmi subsp. americana zorgde in de jaren zeventig er voor dat veel bomen in Nederland afstierven. Na het jaar 2000 kwam er een nieuwe ziektegolf in Nederland, die onder de overgebleven bomen en nieuwe aanplant flink huishoudt.
Ophiostoma novo-ulmi vormt twee soorten conidia. In het xyleem van levende iepen worden in het sporothrix stadium op korte, 10 - 30 µm lange conidioforen ovale conidia gevormd. Deze conidia vermeerderen zich in de xyleemvaten net zoals gisten door knopvorming. Ze kiemen en verspreiden zo het mycelium door de boom. De schimmeldraden zijn 1 - 6 µm dikke en hebben tussenwanden. In afstervende of pas afgestorven bomen vormen in het graphium stadium gekiemde conidia in de bast en in de door de kevers gegraven gangen mycelium, dat kleverige conidia op rechtopgaande, donker gekleurde, 1 -2 mm lange coremia met een bijna kleurloze ronde kop vormt. De kevers verspreiden de kleverige sporen naar andere bomen.[2]
De schimmel is heterothallisch. Als twee verschillende paringstypen op iepenhout elkaar tegenkomen worden perithecia gevormd. De zwarte voet van het perithecium is rond. De Euraziatische ondersoort heeft 75-500 µm brede perithecia met een zwarte nek, die 290 - 640 µm lang is. De Noord-Amerikaanse ondersoort heeft 90-140 µm brede perithecia met een zwarte nek, die 190 - 380 µm lang is. De gesepteerde hyfen zijn 20 - 60 x 1 - 2 µm groot. De dunwandige, doorzichtige sporenzakjes zijn rond tot ovaal. De 4,5 - 6 x 1 - 1,5 µm grote ascosporen hebben geen tussenwanden en zitten in kleverige hoopjes, die door de kevers verspreid worden.[3]
Perithecium van Ophiostoma ulmi
Sporothrix stadium van Ophiostoma ulmi: 4. Conidioforen met conidia
Graphium stadium van Ophiostoma ulmi: Coremium met conidia
Ophiostoma novo-ulmi is een schimmel die behoort tot de orde Ophiostomatales van de ascomyceten. De schimmel veroorzaakt iepenziekte. Ophiostoma novo-ulmi is pas in de jaren zeventig voor het eerst waargenomen en tast ook de tegen Ophiostoma ulmi resistente rassen 'Commelin' en 'Groeneveld' aan. De schimmel heeft n = 8 chromosomen.
Er zijn twee ondersoorten van Ophiostoma novo-ulmi:
De Euraziatische ondersoort (EAN) Ophiostoma novo-ulmi subsp. novo-ulmi Brasier 1991. De Noord-Amerikaanse ondersoort (NAN) Ophiostoma novo-ulmi subsp. americana Brasier & S.A. Kirk 2001.De schimmel groeit in houtvaten van de boom. De boom produceert als reactie thyllen, een gomblaas om de groei van de schimmel te stoppen, maar daardoor raken die vaten ook verstopt. De schimmel kan van het ene houtvat in het andere komen waardoor er zoveel houtvaten verstopt raken dat de boom afsterft. De schimmel wordt verspreid door de grote en de kleine iepenspintkever (Scolytus scolytus en S. multistriatus).
Ophiostoma novo-ulmi Brasier – gatunek grzybów z rodziny Ophiostomataceae[1].
Pozycja w klasyfikacji według Index Fungorum: Ophiostoma, Ophiostomataceae, Ophiostomatales, Sordariomycetidae, Sordariomycetes, Pezizomycotina, Ascomycota, Fungi[1].
Ophiostoma novo-ulmi to pasożyt obligatoryjny przenoszony przez chrząszcze ogłodka wiązowca (Scolytus scolytus) i ogłodka wielorzędowego (Scolytus multistriatus). Żerują one pod korą osłabionych wiązów oraz ich ściętych pni, tworząc tam korytarze. W korytarzach tych znajdują się zarodniki grzyba. Gdy chrząszcze przenoszą się na młode gałązki lub rozwidlenia pędów, przenoszą zarodniki grzyba. Krążące w naczyniach drzewa soki roślinne roznoszą zarodniki po całym drzewie. Rozwijająca się z nich grzybnia początkowo rozwija się w naczyniach, później rozprzestrzenia się na pozostałe tkanki, wytwarzając przy tym bardzo liczne zarodniki konidialne. Są one śluzowate i przyklejają się do ciała chrząszczy, które roznoszą je na następne wiązy[3].
Prawdopodobnie pochodzi z Azji. W Europie i w Ameryce Północnej wraz z gatunkiem Ophiostoma ulmi w XX wieku spowodował dwie wielkie pandemie choroby zwanej holenderską chorobą wiązów. Występujące w Europie gatunki wiązów okazały się bardziej podatne na tę chorobę, niż gatunki azjatyckie. Obecnie choroba już na większości obszaru Europy zanikła, nadal jednak rozprzestrzenia się w północnej części Europy, zwłaszcza w Szkocji. Postępujące ocieplenie klimatu może sprzyjać postępowi tej choroby (i wywołujących ją patogenów) na północ[4].
Ophiostoma novo-ulmi jest ponadto przenosicielem szkodliwych wirusów[4].
Ophiostoma novo-ulmi Brasier – gatunek grzybów z rodziny Ophiostomataceae.
Ophiostoma novo-ulmi je grzib[1], co go ôpisoł Brasier 1991. Ophiostoma novo-ulmi nŏleży do zorty Ophiostoma i familije Ophiostomataceae.[2][3][4]
Wikispecies mo informacyje ô Ophiostoma novo-ulmi.Ophiostoma novo-ulmi je grzib, co go ôpisoł Brasier 1991. Ophiostoma novo-ulmi nŏleży do zorty Ophiostoma i familije Ophiostomataceae.
